Suspicious Process Access via Direct System Calledit

Identifies suspicious process access events from an unknown memory region. Endpoint security solutions usually hook userland Windows APIs in order to decide if the code that is being executed is malicious or not. It’s possible to bypass hooked functions by writing malicious functions that call syscalls directly.

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-windows.*

Severity: high

Risk score: 73

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100



  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Defense Evasion

Version: 3 (version history)

Added (Elastic Stack release): 7.16.0

Last modified (Elastic Stack release): 8.2.0

Rule authors: Elastic

Rule license: Elastic License v2

Investigation guideedit

## Config

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.

Rule queryedit

process where event.code == "10" and
length(winlog.event_data.CallTrace) > 0 and /* Sysmon CallTrace
starting with unknown memory module instead of ntdll which host
Windows NT Syscalls */ not winlog.event_data.CallTrace :

Threat mappingedit


Rule version historyedit

Version 3 (8.2.0 release)
  • Formatting only
Version 2 (8.0.0 release)
  • Formatting only